I just read through about a dozen of the archive posts on this topic cuz I know it's been brought up time and time again, except for this. I just got a NWC T5 completely rebuilt with no miles yes, and no fluid in it yet. Now I understand that it being an 85 trans and not a WC that I should use Gear Oil. I've also read that Redline MTL is also very good quality. So which is the overall best bet and WHY? I don't want someone to just say "this is what I use and it works", I wanna know why I should use one over the other, becuase I want the best possible and I want to know i'm getting the best possible. So which is it?? Going with a Straight gear oil like 85-90, going with a synthetic gear oil 85-90 (valvoline or Mobil1), or going with Redline MTL? I appreciate all responses in the midst of this repetetivness, but I couldn't find this answered anywhere. Thanks guys.

 

It's not that hard, really....

Red Line MTL is synthetic gear lube. It's a little thinner than some others, which is what this trans prefers.

I've used that, and Mobil 1 gear lube (75W-90 IIRC), and can't tell much of a difference as far as how it works. When I had that kind of trans I tore it up so often I can't say whether either one was better than the other. Either would work just fine.

Stay away from the real thick stuff, like Lakewood BFL, it's the wrong thing for that trans.